I'm a senior reporter for the Daily and Sunday Telegraph. This is my personal blog. I'm also cycling commissioner for London, but nothing below represents the view of the GLA or the mayor. For that, go to the official City Hall cycling blog.

Ken Livingstone’s fares cut: could it backfire?

Ed Balls, Labour shadow chancellor, yesterday: “No matter how much we dislike particular Tory spending cuts or tax rises, we cannot make promises now to reverse them. …We will never have credibility unless we have the discipline and the strength to take tough decisions.”

Ken Livingstone, Labour candidate for mayor, yesterday: ‘The detail is simple. I will introduce an overall fares cut of 5% in the autumn of 2012 and ensure there are no further fare rises at all in 2013. In January 2014 and in subsequent years, fares would rise by no more than the price of RPI inflation.”

The detail is not, of course, simple. Ken’s pledge to cut fares is not new – he first made it in January last year. Then, he proposed to finance it “through the restoration of the western extension [of the congestion charge], alongside the introduction of a higher £25 charge for the most-polluting gas guzzlers."

Subsequently, however, Ken dropped plans to reinstate the western extension. And earlier this year, presumably because he could no longer afford it, he also dropped his promise to cut fares, pledging merely “no fare increases above inflation.”

In Ken’s favour is the fact that London transport fares definitely ought to be lower. An annual all-zones London travelcard (£2016 even before next year’s increase) costs not far off treble its equivalent in New York (£797) and more than double its equivalent in the Paris/ Ile-de-France region (£965). You can get an annual pass covering virtually every bus, train and ferry in the entire nation of Switzerland (£2347) for only a few hundred pounds more than an annual ticket from Edgware to Warren Street.

Without the Western Extension revenue, Ken now claims he can pay for his new bout of largesse through an alleged £728 million “operating surplus” in TfL’s budget. The existence of this money is flatly denied by TfL’s deputy chairman, Daniel Moylan. “He got his figure by comparing the current business plan with one set before the government came in and took £2 billion away from us [under the spending cuts],” Moylan says.

“The £728 million does not exist. It’s not there as a cash sum. It was used to offset part of our £2 billion reduction in grant. There is no fairy money under a toadstool – Ken is kippered on this. He hasn’t done his research properly.” The money could still be found, of course – but services or capital programmes would have to be cut. (I did put in a call to Ken's people asking where they'd got their figure from, but they haven't got back to me.)

The danger of the fares pledge for Ken is that it reminds people of what, according to the polls, is his greatest weakness – his dishonesty.

His claims to be a fare-cutter are contradicted by his record. Between 2005 and 2007, to take one example, the single Oyster bus fare under Ken rose by 42 per cent (from 70p to £1). In one year alone, 2007, there was a 25 per cent increase in the off-peak Oyster bus fare, greater than any rise Boris has imposed on it. Over the course of his second term, his fares rose by much the same as Boris’s – without even the excuse of a government spending crisis and Crossrail to pay for.

A few months before the 2008 election, Ken cut the Oyster bus fare from £1 to 90p – and went to the polls pledging not to raise fares by any more than inflation. This turned out to be a lie. Emails leaked to me and the BBC showed that once safely re-installed in City Hall, he was secretly planning massive fare increases, while telling the public the exact opposite. The same pattern was observed around the 2004 elections; fares were cut in real terms before polling day, then rose sharply afterwards.

Fares, in short, have shown Ken at his most cynical and manipulative. Yesterday, even his biggest media groupie, the Guardian’s Dave Hill, felt obliged to question whether people “trust Ken Livingstone to deliver lower fares.” Buying votes could be a good policy for Ken: it doesn't look like he'll get them any other way. But it could just as easily backfire, fuelling all the doubts about his sums and his character.